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- Author or Editor: P. Vukotić x
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Abstract
The instrumental neutron activation analysis method was used for determination of 12 rare earth elements in red and white bauxites. Consideration was given to those systematic errors which in a relative method of analysis can result from the effects of neutron self-shielding, photon self-absorption and fission interfering reactions, due to different chemical composition of bauxite samples and the standard of silicate rock. Also presented is the characteristics “V” shaped chondrite normalized rare earth pattern of white bauxites.
Abstract
By means of thermal neutron activation and countings on the small planar and large coaxial Ge(Li) detector, 13 elements are determined in various silicate rocks, using short-lived radionuclides with half-lives from 2 min to 15 h. A method of routine analysis with simple dead-time and pile-up correction is described and tested with the standard rocks AGV-1 and G-2.
Abstract
-energy for calibrated point sources at a reference distance), (2) detector type and configuration (active body and inactive layers, end cap, windows, housing, shielding, (3) source data (dimension and composition of both container and active material), (4) source-detector geometry (distance, intercepting layers and their composition) and (5) some computational data (Gauss integration coefficients). Gamma-attenuation is calculated upon an extensive (per element and per energy) data file. In the output, efficiency vs. -energy is found, both in forms of tables and graphs. In routine applications accuracies of 3–4% are achieved (not worse than 7% for the most unfavourable geometries). Computation times when using recent PC models are of the order of minutes. ANGLE frame is also easily adjustable to other semiempirical or Monte Carlo models for efficiency calculations.Abstract
Neutron-flux behaviour during irradiation should be known when applying the ko-method of neutron activation analysis /NAA/. During two 100-hour operating periods of the TRIGA MARK II reactor, Ljubljana, the flux was measured by means of a197Au/n,
/198Au monitor /E
=411.8 keV/. Cadmium-covered irradiations were also performed to obtain the epithermal flux and thermal-to-epithermal flux ratio variations. Consistency was found between these results and the reactor operators' logbook record.
Abstract
is extended to cases of parallel but not coincident axes of the cylindrical sources and detectors. True coincidence effects, which introduce typically 5% errors for the counting geometry used, are not dealt with.Abstract
A coincidence method for measuring 137Cs, 40K, 226Ra and 232Th decay products activity in soil, vegetation and fish samples, was applied to the six-crystal gamma-coincidence spectrometer PRIPYAT-2M. In this way, some problems appeared in simultaneous measurement of 137Cs, 226Ra and 232Th by NaI(Tl) detectors and the PRIPYAT-2M spectrometer were solved. The obtained results were agreeable with the HPGe spectrometer ones.
Abstract
The nonideality of the epithermal neutron flux distribution at a reactor site can be described by a 1/E1+
spectrum representation, with parameter being a measure of the nonideality. -values were determined in 3 typical irradiation positions of the TRIGA MARK II reactor of the 
Jozef Stefan
Institute, Ljubljana, Yugoslavia, using the Cd-ratio for multi-monitor method. The simpler Cd-ratio for dual monitor method (monitors:197Au–94Zr) also yielded reliable results. This characterisation is of use in the k0-method of NAA, which is recently introduced at the Institute.
Abstract
Abstract
Environmental radioactivity has been investigated on the Montenegrin Coast (Yugoslavia). Radioactivity was measured on 14 beaches and 5 hinterland localities by a method of in situ gamma-spectrometry. At each measuring site two photon countings were performed — in ground and above it. Specific activities of40K,232Th,238U,137Cs and corresponding exposure rates were then obtained from gamma-spectra and appropriate radiation field models. The results show a washing out effect of the sea-water: radioactivity level on the beach is significantly lower than on its hinterland. In situ spectrometry was also performed inside 16 hotels on the Coast. Radioactivity of building materials is found to be 8 to 20 times lower than the limit permitted by regulations. In 12 of these hotels, indoor radon concentrations were measured with track etch detectors. Winter radon concentrations were in a range (22–90) Bq/m3, i.e., much below the most stringent reference level.
